Scaphoid nonunions: a 3-dimensional analysis of patterns of deformity

Scaphoid Length Loss Following Nonunion Is Associated with Dorsal Intercalated Segment Instability

Background  Dorsal intercalated segment instability (DISI) in scaphoid nonunions is frequently attributed to fracture location relative to ligamentous attachments onto the scaphoid apex. We hypothesize scaphoid length loss to have a stronger correlation with DISI deformity than fracture location in patients with scaphoid nonunion. Questions/Purposes  To investigate the correlation between (1) scaphoid length loss, (2) fracture location relative to the scaphoid apex, and (3) type of nonunion (Herbert classification) and DISI deformity in skeletally mature patients with scaphoid nonunion. Patients and Methods  Twenty-seven cases of computed tomography (CT)-confirmed scaphoid nonunion (>6 months) were retrospectively included. Our primary outcome was the degree of DISI as measured by the radiolunate (RL) angle on CT. Scaphoid length loss was expressed as height-to-length (H/L) ratio. Fracture location was classified as proximal or distal to the scaphoid apex. Nonunions were classified as fibrous unions (type D1) or pseudoarthrosis (type D2). The correlation between RL angle, H/L ratio, fracture location, and nonunion type was evaluated. Results  H/L ratio was the only factor associated with the degree of DISI as measured by RL angle. As scaphoid length loss increased (increasing H/L ratio), the RL angle increased. There was no significant difference in RL angle between fractures located proximal (30 degrees) or distal (28 degrees) to the scaphoid apex, or type D1 (31 degrees) versus type D2 (28 degrees) nonunions. There was no correlation between patient age, sex, or wrist side affected and RL angle. Conclusions  Scaphoid length loss, rather than fracture location, is correlated to the degree of DISI deformity in patients with scaphoid nonunion. This highlights the importance of restoring scaphoid height when planning scaphoid nonunion reconstruction. Level of Evidence  Level III, diagnostic study.

Quantitative 3-D CT Demonstrates Distal Row Pronation and Translation and Radiolunate Arthritis in the SNAC Wrist

BACKGROUND

In scaphoid nonunion advanced collapse (SNAC) wrist arthritis, we analyzed the 3-dimensional (3-D) deformity patterns of carpal alignment secondary to scaphoid nonunion and quantified subchondral arthritis by investigating alterations in bone density.

METHODS

We constructed 3-D models of the carpal bones and radius from 51 patients with scaphoid nonunion (nonunion group) and 50 healthy controls (control group). We quantified the differences in 3-D geometric position of the distal carpal row relative to the distal radius in SNAC wrists versus controls. In addition, we assessed the bone density of anatomic regions of interest in the radiocarpal and capitolunate joints relative to the pisiform bone density to characterize degenerative changes in SNAC wrists.

RESULTS

The distal carpal row pronated by a difference of 14° (7.2° versus -6.7°; p < 0.001), deviated ulnarly by a difference of 19° (7.7° versus -11.2°; p < 0.001), shifted dorsally by a difference of 17% of the dorsovolar width of the distal radius (21.0% versus 4.4%; p < 0.001), shifted radially by a difference of 8% of the radioulnar width of the distal radius (13.2% versus 5.3%; p < 0.001), and migrated proximally by a difference of 12% of the lunate height (96.3% versus 108.8%; p < 0.001) in the nonunion group compared with the control group. Additionally, it was found that bone density was greater at the capitolunate joint (capitate head: 140.4% versus 123.7%; p < 0.001; distal lunate: 159.9% versus 146.3%; p < 0.001), the radial styloid (157.0% versus 136.3%; p < 0.001), and the radiolunate joint (proximal lunate: 134.8% versus 122.7%; p < 0.001; lunate fossa: 158.6% versus 148.1%; p = 0.005) in the nonunion group compared with the control group.

CONCLUSIONS

Scaphoid nonunion exhibited a unique deformity pattern and alteration in bone-density distributions. The distal carpal row not only shifted dorsally and migrated proximally but also pronated, deviated ulnarly, and shifted radially. Bone density was greater at the capitolunate joint, the radial styloid, and surprisingly, the radiolunate joint. Our findings give insight into the natural history and progression of arthritis of the SNAC wrist. Additionally, future studies may give insight into whether successful treatment of scaphoid nonunion arrests the progression of arthritis.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

The influence of fracture location and comminution on acute scaphoid fracture displacement: three-dimensional CT analysis

We aimed to assess the influence of fracture location and comminution on acute scaphoid fracture displacement using three-dimensional CT. CT scans of 51 adults with an acute scaphoid fracture were included. Three-dimensional CT was used to assess fracture location, comminution and displacement. Fracture location was expressed as the height of the cortical breach on the volar and dorsal side of the scaphoid relative to total scaphoid length (%), corresponding to the fracture's entry and exit point, respectively. We found a near-linear relation between dorsal fracture location and displacement. As dorsal fracture location became more distal, translation (ulnar, proximal, volar) and angulation (flexion, pronation) of the distal fragment relative to the proximal fragment increased. Comminuted fractures had more displacement. Dorsal fracture location predictably dictates the direction of translation and angulation in displaced scaphoid fractures. Surgeon attention to dorsal fracture location can help identify displacement patterns and provide guidance in adequately reducing a displaced scaphoid fracture.Level of evidence: III.

MRI of the Wrist Ligaments

Technological advances in magnetic resonance imaging (MRI) have improved radiologists' ability to evaluate wrist ligaments. MRI interpretation often guides clinical management. This article aims to review the normal and pathologic appearance of intrinsic and extrinsic wrist ligaments with a focus on MRI. Variant anatomy, imaging pearls, and clinical significance are also discussed. Special attention is paid to key wrist ligaments that play a role in carpal stability.

Are Vascularized Periosteal Flaps Useful for the Treatment of Difficult Scaphoid Nonunion in Adults? A Prospective Cohort Study of 32 Patients

PURPOSE

To evaluate clinical and radiological outcomes after surgical treatment of difficult scaphoid nonunion in adults with a vascularized thumb metacarpal periosteal pedicled flap (VTMPF).

MATERIALS AND METHODS

Thirty-two patients at least 18 years old, with scaphoid nonunion and characteristics associated with a poor prognosis, who underwent a VTMPF procedure, were included in this retrospective cohort study with a mean follow-up of 17 months. Factors associated with a poor prognosis were a delay in presentation of over 5 years, the presence of avascular necrosis, and previous nonunion surgery. All patients had at least 1 poor prognostic factor and 25% had 2 or more.

RESULTS

In 30 men and 2 women, the mean age was 36 years (range, 19-56 years). There were 11 type D3 nonunions (Herbert classification) and 15 type D4. Five patients had delayed presentation of over 5 years. Fourteen patients had previously undergone an unsuccessful surgical attempt to treat their nonunion. The patients experienced no postoperative complications. Overall union rate was 97% (31 of 32 patients), with 72% cross-sectional trabecular percentage bridging at 12 weeks. Pain subsided after surgery and patients experienced improvements in both their Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and Modified Mayo Wrist Score (MMWS). Overall 41% and 42% gains in strength and wrist motion, relative to the contralateral normal side, were observed. At final follow-up, there were no differences between the treated and the untreated (healthy) hands, in terms of wrist range of motion, grip, or pinch strength.

CONCLUSIONS

In this study, the use of VTMPF for difficult scaphoid nonunion in adults was associated with good general outcomes.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

[3D Imaging for the analysis of scaphoid fractures and non-unions]

The aim of the present study is to give an overview over the possibilities of 3D imaging in the analysis of scaphoid fractures and non-unions and to discuss them on the base of case studies and literature.

Understanding the Patterns of Deformity of Wrist Fractures Using Computer Analysis

Computer modeling of the wrist has followed other fields in the search for descriptive methods to understand the biomechanics of injury. Using patient-specific 3D computer models, we may better understand the biomechanics of wrist fractures in order to plan better care. We may better estimate fracture morphology and stability and evaluate surgical indications, design more adequate or effective surgical approaches and develop novel methods of therapy. The purpose of this review is to question the actual advances made in the understanding of wrist fractures using computer models.

Outcomes of Local Bone Graft and Fixation of Proximal Pole Scaphoid Nascent Nonunions and Nonunions

Background  Fractures of the proximal pole of the scaphoid have an increased risk of nonunion due to its tenuous blood supply. The optimal treatment of proximal pole scaphoid nonunions remains controversial. Objectives  To review a single surgeon's experience with proximal pole scaphoid nascent nonunions (delayed unions) and nonunions that underwent surgical fixation with a cannulated headless compression screw and local autologous bone graft from the distal radius. Patients and Methods  After obtaining Institutional Review Board approval, the electronic medical record of one tertiary care center was queried for patients with the diagnosis of "proximal pole scaphoid fractures" who underwent surgical fixation by a single surgeon over an 11-year period (2006-2017). Fifteen patients met initial query criteria; upon review of records, four patients were excluded due to the acute nature of the fracture, and one was excluded as surgical fixation included a vascularized bone graft. Results  The final study cohort consisted of 10 patients with a total of 10 proximal pole scaphoid nonunions. Almost all of the patients in this study were male (9/10 [90%]), and sporting activities were the most common mechanism of injury (8/10 [80%]). Volumetric measurements of the scaphoid fractures on computed tomography (CT) revealed that the mean total volume of the scaphoid was 2.4 ± 0.48 cm ³ and the mean volume of the proximal pole fragment was 0.38 ± 0.15 cm ³ . Postoperative CT scans were performed at a mean of 12.4 weeks (range: 8-16 weeks), with seven (7/10 [70%]) showing signs of complete union and three (3/10 [30%]) demonstrating partial union. None of the patients required additional procedures and there were no complications. Conclusions  Our results suggest that proximal pole scaphoid fractures with delayed union and nonunion treated with surgical fixation and autologous local bone graft heal without the need for more complex vascularized procedures. The volume of the proximal pole fragment did not correlate with increased risk of ongoing nonunion after the index procedure. Level of Evidence  This is a Level IV, case series study.

Accuracy of manual and automatic placement of an anatomical coordinate system for the full or partial radius in 3D space

Accurate placement of a coordinate system on the radius is important to quantitatively report 3D surgical planning parameters or joint kinematics using 4D imaging techniques. In clinical practice, the scanned length of the radial shaft varies among scanning protocols and scientific studies. The error in positioning a radial coordinate system using a partially scanned radius is unknown. This study investigates whether the imaged length of the radius significantly affects the positioning of the coordinate system. For different lengths of the radius, the error of positioning a coordinate system was determined when placed automatically or manually. A total of 85 healthy radii were systematically shortened until 10% of the distal radius remained. Coordinate systems were placed automatically and manually at each shortening step. A linear mixed model was used to associate the positioning error with the length of the radial shaft. The accuracy and precision of radial coordinate system placement were compared between automatic and manual placement. For automatic placement of the radial coordinate system, an increasing positioning error was associated with an increased shortening of the radius (P = < 0.001). Automatic placement is superior to manual placement; however, if less than 20% of the radial shaft length remains, manual placement is more accurate.

Carpal kinematic changes after scaphoid nonunion: an in vivo study with four-dimensional CT imaging

The aim was to evaluate if motion between the scaphoid bone fragments is related to the position of the fracture line and if a scaphoid nonunion results in the uncoupling of the proximal and distal carpal row during wrist motion. The influence of dorsal intercalated segment instability on interfragmentary motion was also analysed. In this study, 12 patients were included with unilateral scaphoid nonunion. Four-dimensional computerized tomography was used to analyse flexion-extension and radioulnar deviation motion of both wrists. We found that an increased instability of the scaphoid fragments is associated with the presence of dorsal intercalated segment instability and is not dependent on the position of the fracture line relative to the scaphoid apex. Additionally, a scaphoid nonunion results in an uncoupling of the carpal rows.

The Author's Technique for the Management of Unstable Scaphoid Nonunions: Tips and Tricks

This article presents historical aspects, rationale, indications, planning, and execution of anterior interpositional bone grafting technique for unstable scaphoid nonunions. The author's original technique considers four points: (1) preoperative planning based on comparative anteroposterior radiographs in maximal ulnar deviation was used to calculate resection zone, size of the graft, and scaphoid length; (2) a volar approach was used; (3) an iliac crest wedge-shaped corticocancellous graft was interposed; and (4) Kirschner wires were inserted for fixation. Contemporary refinements of the technique including a modification to treat nonunions with failed previous screw fixation with tricks and hints and results are shown.

Diagnosis and Management of Acute Scaphoid Fractures

The scaphoid is the most commonly fractured carpal bone; despite its frequent injury, the diagnosis of fracture can be complicated by the presence of normal radiographs at the time of presentation. Clinical intuition can be increased by physical examination and immediately available modalities such as ultrasound within the emergency department. Definitive diagnosis should be made with computed tomography and magnetic resonance to verify the presence of displacement. This article provides an overview of the incidence and presentation of acute scaphoid fractures with a surgical focus on percutaneous dorsal screw fixation.

Anatomy and injuries of the pediatric wrist: beyond the basics

Ligamentous injuries of the pediatric wrist, once thought to be relatively uncommon, are increasingly recognized in the context of acute high-energy mechanism trauma and chronic axial loading, including those encountered in both recreational and high-performance competitive sports. Recent advances in MR-based techniques for imaging the pediatric wrist allow for sensitive identification of these often radiographically occult injuries. Detailed knowledge of the intrinsic and supportive extrinsic ligamentous complexes, as well as normal developmental anatomy and congenital variation, are essential to accurately diagnose injuries to these structures. Early identification of ligamentous injury of the pediatric wrist is essential within the conservative treatment culture of modern pediatric orthopedics because treatment of these lesions often necessitates surgery, and outcomes often depend on early and sometimes aggressive intervention. In this article, we review MR arthrogram technique and pediatric wrist anatomy, and correlate appearances on MR and selected ligamentous pathologies of the pediatric wrist.

Current Management of Scaphoid Nonunion Based on the Biomechanical Study

Scaphoid nonunion causes abnormal wrist kinematics and typically leads to carpal collapse and subsequent degenerative arthritis of the wrist. However, the natural history, including carpal collapse and degenerative arthritis of scaphoid nonunion, may vary at different fracture locations. This article reviews recent biomechanical studies related to the natural history of scaphoid nonunion. In the distal-type fractures (type B2 in Herbert classification), where the fracture located distal to the scaphoid apex, the proximal scaphoid fragment and lunate, which are connected through the dorsal scapholunate interosseous ligament (DSLIL) and dorsal intercarpal ligament (DIC), extend together, and the distal fragment of the scaphoid flexes individually. Therefore, untreated type B2 fractures normally show the humpback deformity, resulting in dorsal intercalated segment instability deformity relatively earlier after the injury. In the proximal-type fractures (type B1), where the fracture is located proximal to the scaphoid apex, the connection between the distal fragment and lunate is preserved through the DSLIL and DIC so that the scaphoid-lunate complex remains stable and the carpal collapse is less severe than that in distal-type fractures. The fracture location relative to the apex of the dorsal scaphoid ridge is a reliable landmark in the determination of the natural history of scaphoid nonunion.

Corticocancellous bone graft vs cancellous bone graft for the management of unstable scaphoid nonunion

INTRODUCTION

This study was undertaken to determine whether corticocancellous bone grafting and cancellous bone grafting differ in terms of bone union rate, restoration of scaphoid anatomy, and wrist function when unstable scaphoid nonunions are concomitantly treated by screw fixation.

MATERIALS AND METHODS

This is retrospective cohort study. In Group A (17 patients), unstable scaphoid nonunion was treated with corticocancellous graft harvested from the iliac crest and headless compression screw using volar approach. In Group B (18 patients), unstable scaphoid nonunion was treated with cancellous graft harvested from the distal radius or iliac crest and headless compression screw using volar approach Mean time to union was measured using CT image. Scaphoid deformity was also measured using lateral intrascaphoid angle and height to length ratio using CT images. Wrist functional status was assessed by measuring grip strength, wrist range of motion, and DASH score at 1 year postoperatively.

RESULTS

Mean time to union was significantly greater in Group A (15 weeks vs. 11 weeks). No significant intergroup difference was observed for lateral intrascaphoid angle and height to length ratio after treatment of scaphoid nonunion. No significant intergroup difference was observed for grip strength, wrist range of motion, or DASH scores at 1 year postoperatively.

CONCLUSIONS

Cancellous bone grafting was found to lead to earlier bone union than corticocancellous bone grafting and to similar restorations of scaphoid deformity and wrist function when scaphoid nonunion was treated by headless compression screw fixation and bone grafting.

LEVEL OF EVIDENCE

Prognostic, III.

Correlation of CT imaging and histology to guide bone graft selection in scaphoid non-union surgery

INTRODUCTION

For the treatment of scaphoid non-unions (SNU), different surgical techniques, including vascularized and non-vascularized bone grafts, are applied. Besides stability, vascularity, and the biological situation at the non-union site are important for healing and the appropriate choice of treatment. We assessed the healing potential of SNUs by histological parameters and compared it to CT parameters of bone structure and fracture location. Based on the results, we developed a CT classification and a treatment algorithm to impact graft selection in SNU surgery.

PATIENTS AND METHODS

Preoperative 2D-CT reformations of 29 patients were analyzed for trabecular structure, sclerosis, and fragmentation of the proximal fragment. The fracture location was assessed on 3D-CT reconstructions and grouped in three zones depending on the potential blood supply. Samples were taken during surgery for histological evaluation. Histological parameters of bone healing were defined and a bone healing capacity score (BHC), reflecting histological bone viability, was calculated. CT findings were compared to BHC, age of SNU, and time to union.

RESULTS

Cases with trabecular structure and without fragmentation showed a statistically significant higher BHC. Time to union was significantly faster if trabecular structure was present and sclerosis was absent. In intraarticular proximal pole non-unions, where no blood supply is assumed, the BHC was statistically significantly lower and time to union was longer compared to SNUs of the other locations. A statistically significant correlation between BHC and time to union was found in the proximal and distal fragment with higher BHC associated with faster healing.

CONCLUSIONS

CT parameters of bone structure and fracture location can reflect histological healing capacity of SNUs. This can guide bone graft selection in SNU surgery.

Is there a trend in CT scanning scaphoid nonunions for deformity assessment?-A systematic review

PURPOSE

The effect of scaphoid nonunion deformity on wrist function is uncertain due to the lack of reliable imaging tools. Advanced three-dimensional (3-D) computed tomography (CT)-based imaging techniques may improve deformity assessment by using a mirrored image of the contralateral intact wrist as anatomic reference. The implementation of such techniques depends on the extent to which conventional CT is currently used in standard practice. The purpose of this systematic review of medical literature was to analyze the trend in CT scanning scaphoid nonunions, either unilaterally or bilaterally.

MATERIALS AND METHODS

Using Medline and Embase databases, two independent reviewers searched for original full-length clinical articles describing series with at least five patients focusing on reconstructive surgery of scaphoid nonunions with bone grafting and/or fixation, from the years 2000-2015. We excluded reports focusing on only nonunions suspected for avascular necrosis and/or treated with vascularized bone grafting, as their workup often includes magnetic resonance imaging. For data analysis, we evaluated the use of CT scans and distinguished between uni- and bilateral, and pre- and postoperative scans.

RESULTS

Seventy-seven articles were included of which 16 were published between 2000 and 2005, 19 between 2006 and 2010, and 42 between 2011 and 2015. For these consecutive intervals, the rates of articles describing the use of pre- and postoperative CT scans increased from 13%, to 16%, to 31%, and from 25%, to 32%, to 52%, respectively. Hereof, only two (3%) articles described the use of bilateral CT scans.

CONCLUSION

There is an evident trend in performing unilateral CT scans before and after reconstructive surgery of a scaphoid nonunion. To improve assessment of scaphoid nonunion deformity using 3-D CT-based imaging techniques, we recommend scanning the contralateral wrist as well.

Rehabilitation for scapholunate injury: Application of scientific and clinical evidence to practice

In this article, the development of a rehabilitation approach is describe using scapholunate injury as a model. We demonstrate how scientific and clinical evidence is applied to a treatment paradigm and modified based on emerging evidence. Role of the scapholunate interosseous ligament within the pathomechanics of the carpus, along with the progression of pathology, and specific rehabilitation algorithms tailored to the stage of injury. We review the recent and current evidence on the kinematics of wrist motion during functional activity, role of the muscles in providing dynamic stability of the carpus, and basic science of proprioception. Key relevant findings in each of these inter-related areas are highlighted to demonstrate how together they form the basis for current wrist rehabilitation. Finally, we make recommendations for future research to further test the efficacy of these approaches in improving functional outcomes.

Three-dimensional analysis of osteophyte formation on distal radius following scaphoid nonunion

BACKGROUND

The purposes of this study were to quantitatively analyze osteophyte formation of the distal radius following scaphoid nonunion and to investigate how fracture locations relate to osteophyte formation patterns.

METHODS

Three-dimensional surface models of the scaphoid and distal radius were constructed from computed tomographic images of both the wrists of 17 patients' with scaphoid nonunion. The scaphoid nonunions were classified into 3 types according to the location of the fracture line: distal extra-articular (n = 6); distal intra-articular (n = 5); and proximal (n = 6). The osteophyte models of the radius were created by subtracting the mirror image of the contralateral radius model from the affected radius model using a Boolean operation. The osteophyte locations on the radius were divided into 5 areas: styloid process, dorsal scaphoid fossa, volar scaphoid fossa, dorsal lunate fossa, and volar lunate fossa. Osteophyte volumes were compared among the areas and types of nonunion. The presence or absence of dorsal intercalated segment instability (DISI) deformity was also determined.

RESULTS

The distal intra-articular type exhibited significantly larger osteophytes in the styloid process than the distal extra-articular type. Furthermore, the proximal type exhibited significantly larger osteophytes in the dorsal scaphoid fossa than the distal extra-articular type. Finally, the distal intra- and extra-articular types were more associated with DISI deformity and tended to have larger osteophytes in the lunate fossa than the proximal type.

CONCLUSION

The pattern of osteophyte formation in the distal radius determined using three-dimensional computed tomography imaging varied among the different types of scaphoid nonunion (distal extra-articular, distal intra-articular, and proximal). The results of this study are clinically useful in determining whether additional resection of osteophytes or radial styloid is necessary or not during the treatment of the scaphoid nonunion.

Analysis of deformity in scaphoid non-unions using two- and three-dimensional imaging

Pre-operative assessment of the deformity in scaphoid non-unions influences surgical decision-making. To characterize deformity, we used three-dimensional computed tomographic modelling in 28 scaphoid non-unions, and quantified bone loss, dorsal osteophyte volume and flexion deformity. We further related these three-dimensional parameters to the intrascaphoid and capitate-lunate angles, and stage of scaphoid non-union advanced collapse assessed on conventional two-dimensional images and to the chosen surgical procedure. Three-dimensional flexion deformity (mean 26°) did not correlate with intrascaphoid and capitate-lunate angles. Osteophyte volume was positively correlated with bone loss and stage of scaphoid non-union advanced collapse. Osteophyte volume and bone loss increased over time. Three-dimensional modelling enables the quantification of bone loss and osteophyte volume, which may be valuable parameters in the characterization of deformity and subsequent decision-making about treatment, when taken in addition to the clinical aspects and level of osteoarthritis.

TYPE OF STUDY/LEVEL OF EVIDENCE

Level IV.

The Effect of Scaphoid Fracture Site on Scaphoid Instability Patterns

Background Scaphoid fractures are common carpal fractures that are often misdiagnosed as wrist sprains and may go on to nonunion. The location of the fracture site may influence the stability of scaphoid nonunions. Purpose To determine whether the stability of a scaphoid nonunion depends upon the fracture's location, we tested the hypothesis that a simulated fracture distal to the apex of the scaphoid dorsal ridge will have greater interfragmentary motion than proximal. Methods Eleven cadaver wrists were moved through three wrist motions using a wrist simulator. In six wrists, a fracture was created distal to the scaphoid apex, and in five a fracture was created proximal to the apex. Sensors attached to the distal and proximal parts of each scaphoid measured the interfragmentary motion during wrist motion. Results In those wrists in which the scaphoid was sectioned distal to the apex, the distal fragment became significantly more unstable relative to the proximal fragment. It flexed, ulnarly deviated, and pronated. These motion changes were less when the scaphoid was sectioned proximally. Discussion Scaphoid fractures distal to the scaphoid apex will have greater interfragmentary motion. The mobility of the fragments at the fracture site is possibly a more important contributory factor of nonunion in scaphoid waist fractures than for proximal scaphoid fractures. Clinical Relevance Understanding the effect that the location of a scaphoid fracture has on the potential for nonunion may influence the modalities of treatment and follow-up.

Computer-Assisted 3-Dimensional Reconstructions of Scaphoid Fractures and Nonunions With and Without the Use of Patient-Specific Guides: Early Clinical Outcomes and Postoperative Assessments of Reconstruction Accuracy

PURPOSE

To present results regarding the accuracy of the reduction of surgically reconstructed scaphoid nonunions or fractures using 3-dimensional computer-based planning with and without patient-specific guides.

METHODS

Computer-based surgical planning was performed with computed tomography (CT) data on 22 patients comparing models of the pathological and the opposite uninjured scaphoid in 3 dimensions. For group 1 (9 patients), patient-specific guides were designed and manufactured using additive manufacturing technology. During surgery, the guides were used to define the orientation of the reduced fragments. The scaphoids in group 2 (13 patients) were reduced with the conventional freehand technique. All scaphoids in both groups were fixed with a headless compression screw or K-wires, and all bone defects (except one) were filled with autologous bone grafts or vascularized grafts. Postoperative CT scans were acquired 2 or more months after the operations to monitor consolidation and compare the final result with the preoperative plan. The clinical results and accuracy of the reconstructions were compared.

RESULTS

In group 1, 8 of 9 scaphoids healed after 2 to 6 months, and partial nonunion after 9 months was observed in one patient. In group 2, 11 of 13 scaphoids healed between 2 and 34 months whereas 2 scaphoids did not consolidate. Comparison of the preoperative and postoperative 3-dimensional data revealed an average residual displacement of 7° (4° in flexion-extension, 4° in ulnar-radial deviation, and 3° in pronation-supination) in group 1. In group 2, residual displacement after surgery was 26° (22° in flexion-extension, 12° in ulnar-radial deviation, and 7° in pronation-supination). The difference in the accuracy of reconstruction was significant.

CONCLUSIONS

Although the scaphoid is small, patient-specific guides can be used to perform scaphoid reconstructions. When the guides were used, the reconstructions were significantly more anatomic compared with those resulting from the freehand technique.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

In vivo three-dimensional elbow biomechanics during forearm rotation

BACKGROUND

It is unclear how elbow kinematics changes during forearm rotation. This study investigated in vivo 3-dimensional elbow kinematics during forearm rotation.

METHODS

We studied 12 normal elbows using in vivo 3-dimensional computed tomography data in maximum forearm supination, neutral, and maximum pronation with the elbows in extension. We measured the motion of the radius and ulna relative to the humerus using a markerless bone registration technique and the contact area of the radiocapitellar joint, proximal radioulnar joint, and ulnohumeral joint using a proximity mapping method.

RESULTS

When the forearm rotated from the supinated position to the pronated position, the radius showed significant varus rotation, internal rotation, and extension relative to the humerus. The center of the radial head significantly translated anteriorly, proximally, and laterally. The ulna significantly rotated in valgus, and the deepest point on the sagittal ridge of the trochlear notch translated medially with forearm pronation. The contact area of the radiocapitellar joint was largest in pronation. The contact area of the proximal radioulnar joint was largest in supination. The contact area of the ulnohumeral joint showed no significant change during forearm rotation.

CONCLUSIONS

In pronation, because of the proximal migration of the radial head, the radiocapitellar joint was most congruent compared with other positions. The proximal radioulnar joint was most congruent in supination. The ulnohumeral joint congruency was not affected by forearm rotation. This study provides useful information for understanding 3-dimensional elbow motion and joint osseous stability related to forearm rotation.

Functional kinematics of the wrist

The purpose of this article is to review past and present concepts concerning functional kinematics of the healthy and injured wrist. To provide a context for students of the wrist, we describe the progression of techniques for measuring carpal kinematics over the past century and discuss how this has influenced today's understanding of functional kinematics. Next, we provide an overview of recent developments and highlight the clinical relevance of these findings. We use these findings and recent evidence that supports the importance of coupled motion in early rehabilitation of radiocarpal injuries to develop the argument that coupled motion during functional activities is a clinically relevant outcome; therefore, clinicians should develop a framework for its dynamic assessment. This should enable a tailored and individualized approach to the treatment of carpal injuries.

Morphological analysis of the acetabular cartilage surface in elderly subjects

PURPOSE

The geometry of acetabular cartilage surface plays an important role in hip joint biomechanics. The aim of this study was to analyze the morphology of acetabular articular cartilage surface in elderly donated bodies to science using a 3D-digitizer.

METHODS

Twenty hemipelves from 12 subjects (mean ages 85 years) were scanned with 3D-digitizer. Each acetabular surface model was divided into four regions: anterosuperior (AS), anteroinferior (AI), posterosuperior (PS), and posteroinferior (PI). In the global acetabulum and each region, the acetabular sphere radius and the standard deviation (SD) of the distance from the acetabular sphere center to the acetabular cartilage surface were calculated. In the global acetabulum, the distance between the acetabular surface model and the maximum sphere which did not penetrate over the acetabular surface model was calculated as the inferred femoral head, and then the distribution was mapped at intervals of 0.5 mm.

RESULTS

The SD in AS was significantly larger than that in AI (p = 0.006) and PI (p = 0.001). The SD in PS was significantly larger than that in PI (p = 0.005). The closest region (0-0.5 mm) tended to be distributed at anterior or posterosuperior acetabular edge.

CONCLUSIONS

The contact between the femoral head and acetabulum might start at the periphery of the lunate surface, especially in the anterior or posterosuperior region. From viewpoint of acetabular morphology, the acetabular articular cartilage in the anterior or posterosuperior edge could be more vulnerable due to direct contact mechanism.

Quantifying scaphoid malalignment based upon height-to-length ratios obtained by 3-dimensional computed tomography

PURPOSE

To determine if 3-dimensional height-to-length (H/L) measurements including coronal plane assessment will improve malalignment detection of scaphoid fractures and to determine if more waist than proximal pole nonunions are malaligned.

METHODS

Computed tomography scans of uninjured wrists (n = 74) were used to obtain 3-dimensional models of healthy scaphoids. These models were used to determine 95% normal ranges of the H/L ratio in standard sagittal and coronal planes in an automated fashion. Subsequently, the H/L ratios of fibrous nonunions (n = 26) were compared with these normal ranges and were classified as either aligned or malaligned.

RESULTS

The mean normal H/L ratio in the sagittal plane was 0.61 (range, 0.54-0.69) and in the coronal plane 0.42 (range, 0.36-0.48). The mean H/L ratios of the nonunions differed from those of the healthy scaphoids in these planes: 0.65 and 0.48, respectively. Based on sagittal plane evaluation of all nonunions, 46% exceeded the normal H/L range versus 54% based on combining sagittal and coronal plane measurements. More waist nonunions (71%) than proximal pole nonunions (22%) exceed the normal H/L range.

CONCLUSIONS

Evaluation of the H/L ratio in the coronal plane provided valuable additional information for the detection of scaphoid deformities. More malaligned cases were found for waist nonunions than for proximal pole nonunions.

CLINICAL RELEVANCE

This method may be a helpful diagnostic tool to detect malalignment and to choose between in situ fixation or reconstruction.

In vivo 3-dimensional analysis of stage III Kienböck disease: pattern of carpal deformity and radioscaphoid joint congruity

PURPOSE

To examine 3-dimensional carpal alignment and radioscaphoid joint (RSJ) congruity among normal wrists and those with Lichtman stage III Kienböck disease or scapholunate dislocation (SLD).

METHODS

We conducted 3-dimensional analysis based on computed tomographic data to compare 10 wrists of stage III Kienböck disease (5 IIIa and 5 IIIb) with 5 normal wrists and 3 wrists with SLD. A markerless bone registration technique was used to investigate the 3-dimensional position of the scaphoid relative to the radius. To evaluate RSJ congruency, the inferred contact area between the scaphoid proximal pole and the distal radius was calculated from 3-dimensional bone models.

RESULTS

The scaphoid position was not significantly different from normal wrists in stage IIIa Kienböck disease. Stage IIIb Kienböck disease was meaningfully associated with a flexed scaphoid and proximal translation of the centroid, but not dorsal translation of the scaphoid proximal pole, where RSJ congruity was preserved. With SLD, the scaphoid flexed to the same extent as that in stage IIIb Kienböck disease, and the proximal pole translated dorsally together with the capitate, producing RSJ incongruity.

CONCLUSIONS

The patterns of carpal collapse differed between stage IIIb Kienböck disease and SLD in terms of RSJ congruity. Our study showed that stage IIIb Kienböck disease did not involve dorsal subluxation of the scaphoid proximal pole and that RSJ congruity was retained, unlike SLD.

CLINICAL RELEVANCE

Our results suggest that carpal collapse in Kienböck disease is not associated with RSJ incongruity, which may explain why there are asymptomatic patients with Kienböck disease and carpal collapse.

A comparison of 3-D computed tomography versus 2-D radiography measurements of ulnar variance and ulnolunate distance during forearm rotation

Positive ulnar variance is associated with ulnar impaction syndrome and ulnar variance is reported to increase with pronation. However, radiographic measurement can be affected markedly by the incident angle of the X-ray beam. We performed three-dimensional (3-D) computed tomography measurements of ulnar variance and ulnolunate distance during forearm rotation and compared these with plain radiographic measurements in 15 healthy wrists. From supination to pronation, ulnar variance increased in all cases on the radiographs; mean ulnar variance increased significantly and mean ulnolunate distance decreased significantly. However on 3-D imaging, ulna variance decreased in 12 cases on moving into pronation and increased in three cases; neither the mean ulnar variance nor mean ulnolunate distance changed significantly. Our results suggest that the forearm position in which ulnar variance increased varies among individuals. This may explain why some patients with ulnar impaction syndrome complain of wrist pain exacerbated by forearm supination. It also suggests that standard radiographic assessments of ulnar variance are unreliable.

Radiographic clues for determining carpal instability and treatment protocol for scaphoid fractures

The magnitude of carpal instability following scaphoid fracture is closely related to the fracture location. Middle-third fractures of the scaphoid are classified into B1 (distal oblique fractures) and B2 (complete waist fractures). Deciding preoperatively whether a fracture is B1 or B2 is clinically important, because several studies have revealed that B1 is more stable than B2. Dorsal intercalated segment instability deformity often develops in B2, creating a large, wedge-shaped bone defect, while minimal humpback deformity develops in B1, and the bone defect is much smaller, even after long-standing nonunions. However, determination of the fracture types using X-rays may be less accurate than using three dimensional computed tomography. This article suggests two radiographic clues for estimation of post-fracture carpal instability along with a treatment protocol for each fracture type.

Three-dimensional suitability assessment of three types of osteochondral autograft for ulnar coronoid process reconstruction

BACKGROUND

Osteochondral autografts with use of the olecranon tip, lateral radial head, or proximal radial head have been employed for coronoid process reconstruction. However, it is unclear which autograft is most suitable for coronoid articular configuration. We assessed 3-dimensional articular facet suitability of 3 osteochondral autografts for coronoid process reconstruction.

METHODS

We performed 3-dimensional computed tomography of 20 elbows to compare the articular facet configuration between the coronoid process and the ipsilateral olecranon tip, lateral radial head, and proximal radial head. We measured the area of the proximity region (≤2.0 mm) between the articular facets of the coronoid process and 3 osteochondral autografts, the covering rate defined as the percentage area of the coronoid articular facet occupied by the proximity region, the location of the proximity region center, and the percentage of the removed ulnohumeral articular facet.

RESULTS

The covering rate was significantly higher with an olecranon graft than with radial head grafts. The regional center of a proximal radial head graft was significantly medial compared with that of olecranon and lateral radial head grafts. The olecranon graft used an average of 13.8% of the ulnohumeral articular facet.

CONCLUSIONS

An olecranon graft was most suitable for defects of the coronoid process involving the tip, and a proximal radial head graft was most suitable for defects of the coronoid process involving the anteromedial rim. The use of an olecranon graft for reconstruction of 50% of the height of the coronoid process does not cause concern for gross elbow instability.

In vivo hip joint contact distribution and bony impingement in normal and dysplastic human hips

Our objectives were to clarify the 3D articular contact areas of the in vivo normal hip joint and acetabular dysplasia during specific positions using magnetic resonance imaging (MRI), voxel-based registration, and proximity mapping. Forty-two normal and 24 dysplastic hips were examined. MRI was performed at four positions: neutral; 45° flexion; 15° extension; and the Patrick position. Femur and pelvis bone models were reconstructed at the neutral position and superimposed over the images of each different position using voxel-based registration. The inferred cartilage contact and bony impingement were investigated using proximity mapping. The femoral head translated in the anterior or posteroinferior, anterosuperior, and posteroinferior direction from neutral to 45° flexion, 15° extension, and the Patrick position, respectively. Multiple regression analyses showed age, femoral head sphericity, and acetabular sphericity to be associated with higher hip instability. The present technique using subject-specific models revealed the in vivo hip joint contact area in a population of healthy individuals and dysplastic patients without radioactive exposure. These results can be used for analyzing disease progression in the dysplastic hip and pathogenesis of acetabular labral tear.

In vivo 3-dimensional analysis of dorsal intercalated segment instability deformity secondary to scapholunate dissociation: a preliminary report

PURPOSE

To investigate in vivo 3-dimensional patterns of dorsal intercalated segment instability deformity resulting from scapholunate dissociation.

METHODS

We studied 6 patients with stage IV scapholunate dissociation in which there were complete tears of the scapholunate interosseous ligament and dorsal intercalated segment instability deformity. Of these, 3 patients had a dorsally displaced distal radius malunion, a condition known to aggravate or produce a dorsal intercalated segment instability deformity. With the wrist in neutral, we created 3-dimensional bone models of the wrists from computed tomography. We calculated centroid locations of each carpal and the rotational angle of the scaphoid and lunate relative to the radius and compared them with those of 6 normal subjects. The joint contact area was visualized to evaluate congruity of the radiocarpal and midcarpal joints.

RESULTS

In the scapholunate dissociated wrists, the scaphoid translated dorsally and radially with rotation in the direction of flexion and pronation. The lunate was extended and supinated. The capitate, trapezoid, and trapezium translated dorsally. Contact area of the radioscaphoid joint shifted dorsoradially owing to dorsoradial subluxation of the scaphoid proximal pole. Congruity was retained in the radiolunate, lunocapitate, and scaphotrapeziotrapezoid joints. In the malunion cases, the scaphoid and distal carpal rows translated more dorsally along dorsal angulation of the distal radius; therefore, incongruity of the radioscaphoid joint became more pronounced.

CONCLUSIONS

Dorsoradial subluxation of the scaphoid proximal pole over the dorsal rim of the radius led to incongruity of the radioscaphoid joint. Dorsal translation of the distal carpal row occurred with maintaining congruency of the radiolunate, lunocapitate, and scaphotrapeziotrapezoid joints. These results suggest that for realignment of the carpal axis of an advanced scapholunate dissociated wrist, we should restore scapholunate rotational malalignment and reduce the dorsally translated distal carpal row back to the anatomical position.

Changes in contact site of the radiocarpal joint and lengths of the carpal ligaments in forearm rotation: an in vivo study

PURPOSE

To examine the contact site of the radiocarpal joint and lengths of carpal ligaments at different forearm rotations in vivo. Rotation of the forearm could exert noteworthy influence on mechanics of the wrist, and understanding how forearm rotation influences wrist mechanics may help treat carpal disorders because wrist position closely relates to forearm rotation.

METHODS

We obtained computed tomography scans of the wrists of 8 volunteers at the following 7 positions of forearm rotation: neutral; 30°, 60°, and 90° of pronation; and 30°, 60°, and 90° of supination. Three-dimensional images of the carpals and distal radius and ulna were reconstructed with software. Subsequently, the contact site of the scaphoid and lunate on the radial articular surface and the lengths of 8 carpal ligaments between their respective origin and insertion points were measured and compared among different positions of forearm rotation.

RESULTS

We found that the contact site of the scaphoid on the distal radius moved between 0.2 and 2.0 mm during forearm rotation. The lengths of the 3 ulnar carpal ligaments (ie, ulnocapitate [UC], ulnolunate [UL], and ulnotriquetral [UT] ligaments) showed the greatest and significant change. From neutral position to pronation, the UC, UL, and UT ligaments shortened significantly. From neutral position to supination, the UT ligament lengthened significantly, but the radioscaphocapitate, UC, UL, and dorsal intercarpal ligaments decreased significantly.

CONCLUSIONS

During forearm rotation, the contact site of the scaphoid and the lunate on the distal radial articular surface changed minimally. The lengths of 3 ulnar carpal ligaments (UC, UL, and UT ligaments) changed substantially.

CLINICAL RELEVANCE

Our findings will help elucidate carpal biomechanics during forearm rotation. The findings may inform decisions about how to reduce the load to these carpal ligaments when treating the carpal disorders.

Diagnostic performance of radiographs and computed tomography for displacement and instability of acute scaphoid waist fractures

BACKGROUND

Fracture displacement is the most important factor associated with nonunion of a scaphoid waist fracture.We evaluated the performance characteristics of radiographs and computed tomography (CT) in the diagnosis of intraoperative displacement and instability of scaphoid waist fractures using wrist arthroscopy as the reference standard.

METHODS

During a six-year period (2004 to 2010) at two institutions, forty-four adult patients with a scaphoid waist fracture underwent arthroscopy-assisted operative fracture treatment at a mean of nine days (range, two to twenty-two days) after injury. Subjects included all of those with a displaced scaphoid fracture seen on radiographs and a selection of patients with a nondisplaced scaphoid fracture. All patients had preoperative radiographs and CT. Arthroscopy with up to 5 kg of traction was the reference standard for fracture displacement and instability.

RESULTS

The reference standard (arthroscopy) led to a diagnosis of twenty-two displaced fractures (all unstable) and twenty-two nondisplaced fractures (seven unstable). Displacement was diagnosed in eleven patients (25%) with the use of radiographs and in twenty (45%) with CT. The sensitivity, specificity, and accuracy for diagnosing intraoperative displacement were 45%, 95%, and 70%, respectively, with the use of radiographs and 77%, 86%, and 82%, respectively, with CT. The sensitivity, specificity, and accuracy for diagnosing intraoperative instability were 34%, 93%, and 55%, respectively,with the use of radiographs and 62%, 87%, and 70%, respectively, with CT. Assuming a 10% prevalence of fracture displacement and instability among all scaphoid waist fractures, the positive and negative predictive values for displacement were 53% and 94%, respectively, with the use of radiographs and 39% and 97% with CT whereas the positive and negative predictive values for instability were 36% and 93%, respectively, with radiographs and 34% and 95% with CT.

CONCLUSIONS

Radiographs and CT scans cannot be relied on to accurately diagnose intraoperative scaphoid fracture displacement or instability compared with arthroscopic examination. The influence, with regard to the risk of nonunion, of intraoperative instability of a scaphoid fracture that is seen to be nondisplaced on radiographs or CT is currently unknown.

LEVEL OF EVIDENCE

Diagnostic Level III.

Scaphocapitolunate arthrodesis and radial styloidectomy: a treatment option for posttraumatic degenerative wrist disease

Longstanding scaphoid nonunion, scaphoid malunion, and chronic scapholunate dissociation result in malalignment of the carpal bones, progressive carpal collapse, instability, and osteoarthritis of the wrist. The most commonly used procedures to treat scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrists are the four-corner fusion (4CF) and the proximal row carpectomy (PRC). Here we describe a different treatment option: radial styloidectomy and scaphocapitolunate (SCL) arthrodesis. This treatment option is chosen in an effort to maintain the joint contact surface and load transmission across the radiocarpal joint. Twenty patients were treated by the senior author (DLF) with this method with a mean follow-up of 4.6 years. Pain decreased in all patients, and 13 patients were pain-free postoperatively. The average Disabilities of the Arm, Shoulder, and Hand (DASH) scores decreased from 44 preoperatively to 23 postoperatively. One patient's course was complicated by nonunion, which was successfully treated with revision of the SCL arthrodesis. On follow-up radiographs, no patient had progressive osteoarthritis. This method preserves the normal ulnar-sided joints of the carpus, which are sacrificed during 4CF, and maintains a more physiologic joint surface for radiocarpal load sharing.

In vivo changes in contact regions of the radiocarpal joint during wrist hyperextension

PURPOSE

Distal radius and scaphoid fractures commonly occur after a fall with the hand outstretched and wrist hyperextended. We investigated contact characteristics of the radiocarpal joint in neutral position, hyperextension, and hyperextension combined with radial deviation in vivo.

METHODS

Eight volunteers without a known history of wrist injury were enrolled. We obtained computed tomography scans with 3-dimensional reconstructions of the subjects' right wrists in neutral, hyperextension, and hyperextension with 10° of radial deviation. The contact regions of the radiocarpal joint were mapped. The direction and distance of changes in the contact region centers were recorded and analyzed.

RESULTS

From neutral position to hyperextension, the contact of the scaphoid substantially shifted from the middle to the dorsal part of the articular surface of the radius in 5 of the 8 wrists. With these wrists further deviated radially, the contact shifted to the surface over the radial styloid. In the other wrists, the contact of the scaphoid remained in the center of the radial articular surface. In all wrists, the contact of the radius on the scaphoid shifted from the proximal lateral surface of the scaphoid to the proximal dorsal surface of the scaphoid, and the contact of the radius on the lunate shifted dorsally.

CONCLUSIONS

During wrist hyperextension, the contact of the scaphoid on the distal radius exhibited 2 possible types of changes: either shifting from the mid-portion to the dorsal ridge of the articular surface of the radius or remaining at the center of the articular surface. Combined wrist hyperextension with radial deviation caused the scaphoid to contact the radius over the radial styloid. The contact of the radius on the scaphoid shifted from proximal lateral to proximal dorsal scaphoid, and that on the lunate shifted dorsally.

CLINICAL RELEVANCE

This study provided in vivo mechanical findings to improve our understanding of the mechanism of hyperextension injuries of carpus.

Three-dimensional motion of the uncovertebral joint during head rotation

Object

The uncovertebral joints are peculiar but clinically important anatomical structures of the cervical vertebrae. In the aged or degenerative cervical spine, osteophytes arising from an uncovertebral joint can cause cervical radiculopathy, often necessitating decompression surgery. Although these joints are believed to bear some relationship to head rotation, how the uncovertebral joints work during head rotation remains unclear. The purpose of this study is to elucidate 3D motion of the uncovertebral joints during head rotation.

Methods

Study participants were 10 healthy volunteers who underwent 3D MRI of the cervical spine in 11 positions during head rotation: neutral (0°) and 15° increments to maximal head rotation on each side (left and right). Relative motions of the cervical spine were calculated by automatically superimposing a segmented 3D MR image of the vertebra in the neutral position over images of each position using the volume registration method. The 3D intervertebral motions of all 10 volunteers were standardized, and the 3D motion of uncovertebral joints was visualized on animations using data for the standardized motion. Inferred contact areas of uncovertebral joints were also calculated using a proximity mapping technique.

Results

The 3D animation of uncovertebral joints during head rotation showed that the joints alternate between contact and separation. Inferred contact areas of uncovertebral joints were situated directly lateral at the middle cervical spine and dorsolateral at the lower cervical spine. With increasing angle of rotation, inferred contact areas increased in the middle cervical spine, whereas areas in the lower cervical spine slightly decreased.

Conclusions

In this study, the 3D motions of uncovertebral joints during head rotation were depicted precisely for the first time.

Scaphocapitolunate arthrodesis and radial styloidectomy for posttraumatic degenerative wrist disease

Long-standing scaphoid nonunion, scaphoid malunion, and chronic scapholunate dissociation result in malalignment of the carpal bones, progressive carpal collapse, instability, and osteoarthritis of the wrist. The most commonly used procedures to treat scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrists are the four-corner fusion (4CF) and the proximal row carpectomy (PRC). The purpose of this study was to evaluate the clinical outcome of a different treatment modality: radial styloidectomy and scaphocapitolunate (SCL) arthrodesis. This treatment option is chosen in an effort to maintain the joint contact surface and load transmission across the radiocarpal joint. We conducted a retrospective review of 20 patients (average age 62 years, range: 27 to 75 years) treated from 1994 to 2010. Seven patients were treated for SNAC, 12 patients for SLAC wrists, and 1 for degenerative joint disease following a transscapho-transcapitate perilunar dislocation. Sixteen patients had Herbert screw fixation, and four had Spider plate fixation. All patients had autologous bone graft used for the arthrodesis. The mean follow-up was 4.6 years (range: 2 to 9.6 years). Patients were evaluated clinically and radiographically. Nineteen of 20 arthrodeses healed on an average of 9.6 weeks. One patient was reoperated 8 months after the initial operation with salvage of the SCL arthrodesis with a spider plate with an adequate result. The mean active flexion-extension arc was 70 degrees and the radioulnar deviation arc was 23 degrees. Pain decreased in all patients, 13 of whom were pain free postoperatively. The average postoperative disabilities of arm, shoulder, and hand score was 24. Radiographically, neither radiolunate nor radioscaphoid arthritis was noted on follow-up. SCL arthrodesis with radial styloidectomy resulted in an adequate residual range of motion and pain relief. This method preserves the normal ulnar sided joints of the carpus and maintains a more physiologic joint surface for radiocarpal load sharing.

Factors associated with arthroscopically determined scaphoid fracture displacement and instability

PURPOSE

To identify factors associated with arthroscopically diagnosed scaphoid fracture displacement and instability.

METHODS

This was a secondary use of data from 2 prospective cohort studies. The studies included 58 consecutive adult patients with a scaphoid fracture who elected arthroscopy-assisted operative fracture treatment: some for displacement, some as part of a prospective protocol, and others to avoid a cast. All patients had preoperative computed tomography with reconstructions in planes defined by the long axis of the scaphoid.

RESULTS

Arthroscopy revealed 38 unstable fractures (movement between fracture fragments; 66%), 27 of which were also displaced. All arthroscopically determined displaced fractures were unstable, and 11 of the 31 arthroscopically determined, nondisplaced fractures were unstable. There was a significant correlation between radiographic comminution (more than 2 fracture fragments) and arthroscopically determined displacement and instability.

CONCLUSIONS

Radiographic comminution is associated with displacement and instability as determined by arthroscopy.

Management of scaphoid nonunion

The primary risk factor for nonunion of the scaphoid is displacement/instability, but delayed or missed diagnosis, inadequate treatment, fracture location, and blood supply are also risk factors. Untreated nonunion leads to degenerative wrist arthritis-the so-called scaphoid nonunion advanced collapse wrist. However, the correlation of symptoms and disease is poor; the true "natural history" is debatable because we evaluate only symptomatic patients presenting for treatment. It is not clear that surgery can change the natural history, even if union is attained. The diagnosis of nonunion is made on radiographs, but computed tomography or magnetic resonance imaging scans can be useful to assess deformity and blood supply. Treatment options vary from percutaneous fixation to open reduction and internal fixation with vascularized or nonvascularized bone grafting to salvage procedures involving excision and/or arthrodesis of carpals.

Three-dimensional distribution of articular cartilage thickness in the elderly talus and calcaneus analyzing the subchondral bone plate density

OBJECTIVE

To unveil the three-dimensional (3D) distribution of talocrural and posterior subtalar articular cartilage thickness in the elderly cadavers using 3D computed tomography (CT) and a 3D-digitizer and to evaluate the relationship between subchondral bone plate density and the overlying cartilage thickness.

DESIGN

Sixteen tali and 16 calcanei from eight cadavers were scanned with 3D-CT to create bone surface models, and with a 3D-digitizer to make cartilage surface models. These two surface models were merged using surface registration method. Articular cartilage thickness was evaluated as the distance between the two models, and the distribution was mapped. The anatomic cartilage thickness of five tali and five calcanei was compared with the distance between the cartilage and bone surface models to calculate optimum threshold for extracting the subchondral bone plate. Generalized estimating equations were used for comparison and measurement errors. Canonical correlation analysis was performed to determine the strength of association between subchondral bone plate threshold and cartilage thickness.

RESULTS

The talar-subtalar articular cartilage tended to be the thickest of the three joints. In the talocrural joint, the anterior region was the thinnest, and increasing cartilage thickness was seen toward the posterior. In the talar-subtalar joint, the central region was the thickest. Mean measurement errors were 0.059±0.066 mm, 0.038±0.040 mm, and 0.018±0.065 mm in the talocrural, talar-subtalar, and calcaneal-subtalar joints, respectively. The canonical correlation coefficient was 0.995 (P<0.001).

CONCLUSIONS

The articular cartilage thickness was distributed in the elderly hindfoot. The subchondral bone plate density was significantly correlated with the anatomic cartilage thickness.

Scaphoid morphology and clinical outcomes in scaphoid reconstructions

Scaphoid malunion and carpal malalignment can result after scaphoid reconstruction, if the two fragments are not properly reduced before fixation. However, currently there is no information about which degree of deformity or malalignment can be tolerated without impairing clinical function. The purpose of this study was to investigate the influence of the scaphoid morphology and carpal alignment on clinical outcomes after scaphoid reconstruction. A total of 65 patients with an average age of 29 years were followed-up after a mean period of 45 months. In all patients, osseous union after a first-time scaphoid reconstruction in the middle third had been confirmed. Scapholunate (SL) and radiolunate (RL) angles were obtained on plain radiographs as were intrascaphoid (ISA) and dorsal cortical (DCA) angles and the height/length (H/L) ratio of the reconstructed scaphoid on computed tomography (CT) scans. These parameters were correlated with clinical outcome measures. RL angles correlated significantly with wrist range of motion, grip strength and pain levels, whilst SL angles, ISA, DCA and H/L ratio failed to show significant correlations. Our data suggest that clinical outcome is correlated with correct restoration of bone morphology and carpal alignment. After reconstruction, the RL angle should not exceed 10°.

DIFFERENCES IN RADIOGRAPHIC FINDINGS BETWEEN SCAPHOID FRACTURE PATTERNS

Scaphoid fracture patterns can be divided into volar and dorsal type using three-dimensional computed tomography. Ninety-nine patients underwent this examination plus radiography to determine how often fracture pattern was identifiable by radiography including proximal fragment ratio (PFR) measurement. Oblique radiographs obtained at 45° of pronation demonstrated a volar displacement in 28 of 37 volar type fractures in three-dimensional computed tomography (76%), while as oblique view with 45° of supination could identify the dorsal type in ten of 18 (56%). PFR showed a significant difference, with means of 0.59 for volar type and 0.43 for dorsal type. Using oblique views in the two rotational directions together with the PFR, the two fracture patterns could be differentiated in 35 of 43 fractures (81%). No differences were evident between the two fracture patterns with respect to prevalence of dorsal intercalated segment instability deformity.

Non-vascularized bone graft with Herbert-type screw fixation for proximal pole scaphoid nonunion

BACKGROUND

Since proximal pole fractures of the scaphoid are frequently overlooked, the poor vascularity in the proximal pole fragment often leads to nonunion. Vascularized bone grafts have been recently tested in cases with scaphoid proximal pole nonunion, but the indication for this treatment has not been well established. Alternatively, we have been treating such patients with a non-vascularized iliac bone graft and Herbert-type screw fixation with considerable success. The purpose of this investigation is to evaluate these cases retrospectively and clarify the surgical efficacy of our procedure.

METHODS

Between 1996 and 2009, 11 consecutive patients with proximal pole scaphoid nonunion were treated with a non-vascularized corticocancellous iliac bone graft and Herbert-type screw fixation. They were all male aged from 12 to 26 years. In two patients, avascular changes were recognized in the proximal pole in preoperative radiographs or MRI. Follow-up ranged from 12 to 76 months.

RESULTS

Bone union was radiographically confirmed in all patients, who returned to their former activities without any complications. The period from operation to union ranged from 12 to 24 weeks. The mean Mayo modified wrist score was 76.4 points preoperatively and 91.4 points postoperatively, and was improved in all cases.

CONCLUSIONS

A non-vascularized iliac bone graft with Herbert-type screw fixation obtained satisfactory clinical and radiographic results in cases with scaphoid proximal pole nonunion, regardless of the vascularity in the proximal fragment.

Changes in shape and length of the collateral and accessory collateral ligaments of the metacarpophalangeal joint during flexion

BACKGROUND

Although the collateral and accessory collateral ligaments of the metacarpophalangeal joint contribute to the stability of this joint, the functional role of the various portions of these ligaments during flexion is unclear. We investigated changes in the three-dimensional shape and length of the collateral and accessory collateral ligaments during flexion to determine how each portion stabilized the metacarpophalangeal joint.

METHODS

Twelve fingers from three embalmed cadavers were examined. The origin and the insertion point of the dorsal, middle, and volar portions of the radial and the ulnar collateral ligament and of the radial and the ulnar accessory collateral ligament were precisely identified. Microcomputed tomograms were obtained at 10° intervals during passive flexion from 0° to 80°. We created three-dimensional models of the metacarpal, the proximal phalange, and the paths of the twelve ligament portions. Finally, we calculated the change in the shape and length of the path of each ligament portion during flexion.

RESULTS

The region of contact between each collateral ligament and the lateral edge of the metacarpal gradually lengthened during flexion of the joint, and the ligament gradually stretched to pass around the convex radial or ulnar surface of the metacarpal head. In contrast, each accessory collateral ligament curved around the volar tubercle of the metacarpal head at all flexion angles. The length of the volar portion of each collateral ligament and the length of the dorsal and middle portions of each accessory collateral ligament underwent little change during flexion. However, the lengths of the dorsal and middle portions of each collateral ligament increased significantly during flexion, and the length of the volar portion of each accessory collateral ligament decreased significantly.

CONCLUSIONS

The collateral and accessory collateral ligaments can each be functionally divided into three portions-dorsal, middle, and volar. The volar portion of each collateral ligament and the dorsal and middle portions of each accessory collateral ligament are nearly isometric, the dorsal and middle portions of each collateral ligament become taut only in flexion, and the volar portion of each accessory collateral ligament becomes taut only in extension.

Analysis of carpal malalignment caused by scaphoid nonunion and evaluation of corrective bone graft on carpal alignment

PURPOSE

To clarify the correlation between a scaphoid deformity and carpal malalignment in patients with scaphoid waist nonunion and to investigate how accurately a corrective bone graft improves carpal malalignment according to the preoperative plan.

METHODS

A total of 38 patients were analyzed retrospectively. Surgery was performed according to the anterior wedge bone graft method described by Fernandez. The scaphoid deformity and carpal malalignment were evaluated by the changes in the intrascaphoid angle (ISA) and axial length (AL) and by the changes in the radiolunate angle (RLA) and scapholunate angle (SLA), respectively, compared with the uninjured side by using standardized x-rays. Each variable was measured at 1 year after surgery. By performing multiple regression analysis, the correlation between the scaphoid deformity and carpal malalignment and between the correction of the scaphoid deformity and the change in carpal alignment were analyzed.

RESULTS

Compared with the uninjured side, the mean respective changes in the ISA, AL, RLA, and SLA were 11°, -1.3 mm, 14°, and 11°, preoperatively. The changes in the RLA and SLA correlated with the change in the ISA, but not with the change in the AL. The mean postoperative corrections of the ISA and AL were 15° from full extension and 1.7 mm, and the changes in the RLA and SLA were 18° and 12° from full extension, respectively. The change in the RLA correlated with the corrections of the ISA and AL. Although the change in the SLA did not correlate with either of them, the mean postoperative SLA was not significantly different from the mean value of the uninjured side.

CONCLUSIONS

The degree of humpback deformity of the scaphoid correlated with the degree of carpal malalignment. The corrective bone graft resulted in the expected recovery of carpal alignment according to the preoperative plan.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Three-dimensional distribution of articular cartilage thickness in the elderly cadaveric acetabulum: a new method using three-dimensional digitizer and CT

OBJECTIVE

The aim of this study was to evaluate the three-dimensional (3D) distribution of the acetabular articular cartilage thickness in cadaveric elderly individuals, measured using a new method with a 3D-digitizer and computed tomography (CT) and to validate this method using a thresholding technique.

DESIGN

Twenty cadaveric hemipelves without fracture, previous hip surgery, or macroscopic degenerative changes were digitized by a 3D-digitizer to make 3D cartilage surface models, and scanned by 3D-CT to create 3D bone surface models. These two surface models were then merged using a surface registration method. Acetabular articular cartilage thickness was evaluated as the distance between the two surface models, and the distribution was mapped. Tests for accuracy and reproducibility were performed by comparing the cartilage thickness of five human femoral heads measured by stereomicroscopy with the distance between the cartilage and bone surface models.

RESULTS

The superolateral cartilage tended to be the thickest in all acetabula. The smallest category (0-0.5 mm) of articular cartilage thickness existed at the posteroinferior lunate surface. In this new method, the mean measurement error was 0.018+/-0.044 mm for the average optimum threshold and the intraclass correlation coefficients were 0.99 in surface registration and 0.94 in data acquisition for reproducibility, indicating high accuracy and reproducibility.

CONCLUSIONS

The proposed method for measuring articular cartilage using a 3D-digitizer and 3D-CT was accurate and reproducible. In the elderly individuals, acetabular articular cartilage tended to be thicker in the superolateral area and there was the thinnest category (0-0.5 mm) on the posteroinferior lunate surface of the acetabulum. The contour generated along 480 Hounsfield units (HU) was closest to the subchondral bone contour in the elderly hip.